Need help!! Hoping someone can help

Hey guys,

I'm fairly new to the forum but I've owned Mazda's for quite a few years now. Ran into an interesting problem the other day with my newest purchase. The guy I bought the truck from made some modifications to it and I would say they weren't the best thought out or completed. One evening while driving home my dash lights, tail lights and corner lights just shut off. I researched and found out the problem could be a dimmer switch. So I found one from another member and had it shipped and I installed it and still no lights. So I dug a little further and found that the wires coming from under the dash up the steering column were melted and bare. Not all of them but a few of them from what I can tell. I contacted the previous owner and he said that he had a toggle switch mounted for his air compressor and left it on and it melted the other ones. I can post pics tomorrow. My question is, am I gonna have to replace that whole harness and how difficult is it or does anyone else have any suggestions. The truck starts and runs fine as far as I can tell, I just don't have the running lights. Headlights and brake lights work fine.

Thanks in advance guys

If there is enough there to work with, you might be able to repair it by splicing in some new wire. If it's only the harness that runs up the column, then you might be able to replace just that section by splicing on a new piece with connectors and hopefully not have to pull the dash. The last resort would be to replace the whole dash harness.

It might not be a bad idea to pull the dash anyway and see what's going on in there. I've seen a few trucks with shorted out wires at the main relay bank - like this one:




You'll also want to find out how he had the system wired because something went wrong. I would make sure all of the wiring is in good shape before repairing just part of it. He shouldn't have had a high draw power wire in that area of the cab. If he did, then you'll need to go back and wire it properly with a relay.

^ hit the nail on the head.

There is no longer any extra wires there, he must have excellent pulled it all out prior to selling. I've looked thru most of the wires in that area and they seem fine but I'm just not totally sure. How hard is it to replace the whole dash harness. I would feel more comfortable just doing the whole thing.

Its not hard at all really

It's not that hard. Just a little work pulling the dash. See Dan Woodlands write up here:

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You'll want to locate a harness first. If you end up finding one in a junkyard, then you can pull that dash first - FOR PRACTICE!

Then you'll need to pull your own and swap them.

If you can see that most of the rest of the wiring is OK, then I would just repair it. What year and model is your truck? Here are a few things to consider:

Combination switch: There are two different combination switch types - one has a 4 terminal connecter and one has a 5 terminal connecter. So you'll want to get the same style harness from a truck with the same combo switch you have. The manual states that once style is found on carb trucks and the other on efi. But some members on here have found the opposite connecter on their truck than what the manual suggest.

Cruise Control: Some of the earlier trucks seem to have been wired for it already - even if not installed. The later model trucks tend not to be pre-wired for it (a plug-and-play harness was included with the cruise kit.) If you don't have factory cruise, then it's not a concern. If you do, then you'll need to get a harness that is also pre-wired from an early model truck - or swap over the detachable cruise harness that is in the later models.

The truck is a 1990 b2200 extended cab. Do you think this is the problem with my running lights?

Most likely, it is. The switches are also prone to getting gummed up. Check out this thread also - it shows how to clean the switch up.





But if you have melted wire, then you definitely need to tend to that.

Yeah that's for sure....I think maybe if I remove the steering wheel and what not I would have plenty of room to splice in a new harness just before the melted area begins. Now to find a harness.

The tricky part about that is finding one. I haven't been able to find any of these trucks in my area. They are few and far between. Any idea on someone who may be able to help me out?

Yes, the instrument cluster lights, the front corner lights, and the tail lights are all on the same circuit from the headlight switch, a different circuit than the front beams.

I don't have a harness, but I'm going to suggest soldering in new harness or new wires, because this is a safety issue. Crimp connectors sometimes vibrate loose, especially if too-large of a size is used.